public override void EnterFormula([NotNull] FormulaParser.FormulaContext context)
{
opStacks.Push(new Stack <string>());
}
/// <summary>
/// Exit a parse tree produced by <see cref="FormulaParser.formula"/>.
/// <para>The default implementation does nothing.</para>
/// </summary>
/// <param name="context">The parse tree.</param>
public virtual void ExitFormula([NotNull] FormulaParser.FormulaContext context)
{
}
